Estimating spatial and temporal variation of evapotranspiration in South Korea

Evapotranspiration (ET) is a critical component of regional water and energy balance. Its spatial and temporal variation is of importance to many economic activities and to management of terrestrial ecosystems. There has been no quantitative attempt to evaluate ET across the geographic areas in Korea. Land surface of a 6 by 6 km area in Gyunggi province, South Korea was divided into a regular grid with a 30m grid spacing and hourly temperature, humidity, wind and solar irradiance was estimated for each grid cell by spatial interpolation of synoptic weather station data. Satellite remote sensing data were used to classify the vegetation type of each grid cell, and the corresponding spatial attributes including soil texture, canopy structure, and phenological features were identified. All data were fed into a standalone version of SiB2 to simulate latent heat flux at each grid cell. A spatial data management system for SiB2 operation was written to extract data1 and data2 for SiB2 from ArcGIS grids which contain both time variant and invariant spatial attributes of a given region. ET estimates at selected grid cells were validated against the actual measurements of latent heat flux by eddy covariance technique. The results showed a strong feasibility of using spatial - data driven land surface models for operational monitoring of regional ET.